As today's data networks become more flexible and powerful, network users use network resources in many different ways. Network resources are used for purposes ranging from data transfer to video on demand. These various usages require differing amounts of bandwidth and other quality of service metrics at different times. Many network users therefore contract for network services through service level agreements (SLAs) with service providers. Pricing for network services depends, amongst other things, upon the availability of the network, as network users do not want to pay for network services during network outages. Therefore, service providers require a means for measuring network availability.
Availability in IP networks is currently difficult to measure. Service measurements currently depend upon counting lost packets and measuring packet latency. When counting lost packets, individual failures tend to get averaged out. For example, a one in one hundred failing becomes a 1% packet loss, no matter how long the failure lasted. There is currently no way to characterize outages in IP networks with respect to time. Thus, it is difficult to provide an SLA for charging a network user with respect to availability.
It would be desirable to be able to measure availability of a network with respect to time, so that service providers can offer superior SLAs.